Plant volatiles as insect attractants

One of the most interesting aspects of coevolution deals with the interrelationship between the 250,000 odd species of flowering plants and the perhaps 500,000 species of insects that are associated with them in various ecosystems. These coevolutionary relationships began in the early Carboniferous period when land plants first began to diversify and insects began to diversify into modern orders. Chemical ecology lies at the interface between these two enormous groups of very different life forms. There are perhaps 100,000 different secondary plant compounds: terpenoids, alkaloids, phenyl propanoids, esters, acids, alcohols, ketones, and aldehydes produced in the chemical factories of the plant kingdom, and the great preponderance of these act as allomones, kairomones, and synomones in regulating and controlling ecology at the plant‐insect interface. This review will explore current knowledge in this area, with emphasis on the chemical communications involved between these two great groups of life forms. Discussion will be directed at the basic principles of chemical communication from emission of the chemical messenger, to receptor organs, and to the chemotactic responses that result.